#include "stdio.h"

int main() {
	int a, b;
	switch (a) {
		case 99~90;
			A;
			break;
		case 80~89:
			B;
			break;
		case 70~79:
			C;
			break;
		case 60~69:
			D;
			break;
		case <60:
			E;
			break;
		default:
			error;
			return 0;
	}
}